The stamping industry has been confounded with a problem, in the scrap regions or addendum, of a stamped part becoming jammed in the scrap-trimming and removal mechanisms. When a stamped part is produced, it often has excess regions or scrap regions, known in the industry as the addendum, owing to the shape of the sheet metal blank from which the stamped part is produced. The addendum is formed because of the necessary amount of sheet metal blank material that is required at various locations of the final part due to the depth of the part drawn within the die cavities. Furthermore, in order that complex contours can be achieved in a final stamped part, the addendum is often contoured itself to avoid wrinkling and undesired stretching in the contours of the final part. By providing a transition of the contour into the addendum, imperfections of the stamped part resulting from the stamping process can be maintained in the addendum. The addendum is then subsequently removed and the final stamped part containing the desired contours remains for use in its given application.
Springback or recoil is a condition that occurs when flat-rolled metal, such as sheet metal, is cold-worked as is common in the stamping industry. Upon release of the forming force, once the initial stamping is completed, the material has a tendency to partially return to its original shape due to the elastic recovery of the material. Springback is known to be influenced by the tensile and yield strengths of the material as well as by thickness, bend radius and the bend angle of the sheet metal resulting from the stamping process. In deep drawn sheet metal parts, recoil of the addendum, caused by the release of the internal stress of the curvature or contour in the addendum, as the addendum is severed from the final part, is not only a dangerous problem from a workplace safety standpoint, but also it effects the flow of scrap in a high efficiency situation such as an assembly line or mass production parts shop.
When the addendum is severed, to form the final part, for example in an assembly line or mass production parts shop situation where the process is likely substantially automated, the scrap region tends to release inconsistently out of the trimming mechanism or scrap cutter on an inconsistent basis and is not released to the proper place and not when the operator desires the scrap to be released from the cutter. The inconsistent release of the scrap from the scrap cutter often causes jams and prevents the scrap from exiting the die via the scrap chute, causing scrap build-up. Furthermore, the inconsistent scrap nesting locations and subsequent build-ups are known to cause damage to the scrap cutter cutting mechanisms as well as damage to the final part in the form of bent or chipped final part edges.
In addition to the aforementioned damage to the cutting edges and the final part, inconsistent release of the addendum from the scrap cutter results in long periods of downtime over a given period for the stamping and cutting machinery while a worker must manually remove the scrap jams in the scrap chute and other places as well as replace or repair damaged cutting edges of the scrap cutter. Therefore, it is desirable to develop a system of inhibiting the recoil of an addendum of a stamped part upon severing.